Closure for plating drum



Dec. 16, 1969 P. w. sANDROcK CLOSURE FOR PLATING DRUM Filed Nov. 4, 1968 INVENTOR PAUL SANDROCK BY adwod, gedaan #ma em' ATTORNEYS United States Patent O U.S. Cl. 204-213 1 Claim ABSTRACT OF THE DISCLOSURE A self-locking closure for a synthetic resin drum for plating, blackening, pickling or the like, the drum being of cylindrical form and having a generally rectangular door opening in its cylindrical side for loading articles to be treated. The closure includes acurved door panel which fits in the opening and which has an external rib along its longitudinal center line. The door is secured to the drum by one or more bent resilient straps with latching blocks at their ends. The center of the strap bears against the rib and the latching blocks engage cooperating external structure on the drum so that the forces tending to push the door open merely increase the latching action of the blocks.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending U.S. application Ser. No. 470,090, tiled July 7, 1965.

BACKGROUND OF THE INVENTION This invention relates to closures for synthetic resin drums for plating, blackening, pickling or the like, hereinafter referred to simply as plating drums. More particularly the invention relates to a self-locking closure for a cylindrical synthetic resin plating drum wherein force' tending to open the door, such as the weight of the articles being plated, increase the latching action of the closure.

Hexagonal plating drums of acid resistant materials such as synthetic resins are commonly used in commercial practice. An example of a cylindrical synthetic resin plating drum is shown in aforementioned pending application Ser. No. 470,090. Most such drums are perforated to admit the electrolytic fluid or other treating liquid in which the drum is immersed.

To facilitate loading and unloading of the articles to be treated, it is desirable to have an opening in the cylindrical surface of the drum extending the full length thereof and having a Width extending at least 60 and preferably 90 of arc around the drums circumference. The door panel for the opening must lit in such a way that the internal cylindrical surface is continuous, uniform and uninterrupted in order to achieve a uniform tumbling action when the drum is rotated about its axis.

While such door panels can be readily designed and fitted, a major problem is securing them in place. The Weight of the articles being treated in the drum may be as much as several hundred pounds. Such loads, together with impact forces, tend to force the door open against its latching mechanism. The problem is particularly pronouneed where the door opening measures more than 60 around the drum circumference.

SUMMARY OF THE INVENTION It is among the objects of the invention to secure a door panel in the loading opening of a plating drum with suflicient latching strength to prevent opening of the panel during operation.

Another object is to secure the door panel in position in such a way that the forces tending to open the door ICC increase the forces which latch the door panel in position.

According to the present invention, these and other objects are achieved in a cylindrical synthetic resin plating drum by providing and applying one or more doublegambrelled spring metal latching straps to the door panel. These straps are preferably equipped with end blocks that can cooperate with jambs or other latching means extending along the sides of the door opening. So long as the central portions of these straps are able to bear against a suitable central structure on the door panel such as `a longitudinally extending rib or bar, any forces tending to urge the door panel away from the drum opening tend to augment the forces holding the door panel in position. As a result, unintended opening of the drum is precluded.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE l is an isometric representation on a small scale of a plating drum having a closure embodying the invention;

FIGURE 2 is a fragmentary sectional view taken on the lines 2 2 of FIGURE l and drawn to a somewhat larger scale;

FIGURE 3 is a cross sectional View taken on the lines 3 3 of FIGURE 2;

FIGURE 4 is a fragmentary sectional View similar to FIGURE 2 but showing the door panel raised from its closed position; and

FIGURE 5 is a cross sectional view similar to FIG- URE 3 showing the door panel and latching strap in exploded relation with the door panel removed from the opening of the drum.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings there is shown a plating drum A of generally cylindrical shape and having an elongated door panel B extending the full length of the drum and secured in place thereon by latching straps C. The door panel B is formed with the same curvature as the drum and extends through about of arc around the drums circumference. The lateral wall of the drum and the door panel are uniformly cylindrical and enclose the space in which articles to be treated are placed and then tumbled when the drum is rotated about its axis.

The drum A is characterized by two similar circular end plates 10 and 11 which close the opposite ends of the drum. Each is provided, over an arc of 270, with an inwardly extending integrally formed peripheral flange (10a and 11a) which supports one end of a sheet 12 of perforated synthetic resin material such as for example polypropylene curved after the fashion of an incomplete cylinder over an arc which measures approximately 270. The remaining 90 of the cylinder circumference is taken up by the door opening for the door panel B. The drum wall so formed is provided with perforations 13 to admit the electrolytic iuid or other treating liquid in which the drum is immersed. Each of the two end plates has a massive outwardly projecting circular extension (eg, 10b in FIGURES 1 and 2) characterized by a central axial opening With a bearing 14 tted therein and adapted to receive one of a pair of coaxial stub axles (not shown) about which the drum is rotated. A gear 15 of generally annular form is bolted to the end plate 10 for driving the drum as is customary in the art.

Extending along the opposite sides of the opening 16 parallel to the axis of the drum are two door jambs 17 which are also formed of a synthetic resin material and which are securely bonded to the sheet. The jambs 17 are of generally rectangular form in cross section, however the lower inside corner is chamferred to admit the door panel B, the cylindrical sheet 12 protruding slightly inwardly relative to the opening in order to form a base against which the door panel B can rest (FIGURE 3). The door also rests against stops 18 secured to the end plates and 11 (FIGURES 2 and 4).

Between the ends plates 10 and 11 and spaced at equal distances from each other and from their respective end plates are two arcuate girth rings 19, each of which takes the form of an incomplete annulus extending most of the way around the drum A but interrupted as shown in FIG- URES 3 and 5 at the opening 16. Here again the girth rings 19 are of the same material as the sheet 12 and are fused or welded thereto as by the application of heat to provide a strong sturdy virtually unitary structure. The rings 19 serve to reinforce, stiifen and strengthen the cylindrical sheet 12 so that it may accommodate unusually large loads.

The door panel A generally comprises a curved sheet 20 formed with substantially the same radius as the drum wall 12 and similarly formed of a synthetic resin material of about the same thickness and with uniformly spaced perforations. Longitudinal side ribs 21 extend along the side edges of the door panel B as shown in FIGURES 3 and 5, the ribs being formed to match the seat of the opening 16 in the plating drum A. This relationship is best shown in FIGURE 3 where the door panel B is shown in its closed position. The side ribs 21 are suitably fused or welded to the sheet 20 and are similarly formed of the synthetic resin material.

The door panel A has curved end plates 22 and 23 at its opposite ends which are curved to approximately the same radius as the sheet 20 and are fused or welded in place so as to iit closely adjacent the end plates 10 and 11 of the drum A. Between the plates 22 and 23 and spaced at equal distances from each other and from the end plates are two curved ribs 24 which are so located as to complete the annulus partially formed by the girth rings 19.

Located in the center of the sheet 20 and extending from end-to-end of the door panel is an external longitudinal bar 25 which cooperates with the latching straps C in a manner to be described below. Handles 26 are secured to the bar 25 such as by welding or fusing at positions adjacent the end plates 22 and 23, the handles 26 being in the form of rectangular blocks.

The door panel B when in position defines with the plating drum A a closed cylindrical chamber for the articles to be treated, the interior surface being uniform and uninterrupted by internal structure throughout the circumference thereof. The perforations in both the drum wall 12 and the door panel sheet 20 admit the plating fluid or other liquid in which the drum is immersed while tumbling the articles to be treated.

The door panel B is secured to the opening 16 in the plating drum A by means of the latching straps C each of which comprises a resilient band 30 of metal bent into the double-gambrelled form shown in FIGURE 5 so as to define a center segment 31, intermediate segments 32 and end segments 33. Latching blocks 34 are secured t0 the end segments 33 on the inward side thereof such as by bolts, machine screws or other suitable means. The strap C in its unexed form as seen in FIGURE 5 is roughly parabolic in shape, but when in use as Seen in FIGURE 3 its shape roughly approximates the arc of a circle.

The rectangular blocks 34 are adapted to cooperate with the door jarnbs 17 and the center segment 31 with the longitudinal bar 25, It will vhe seen from FIGURE 3 that the center segment 31 bears directly against bar 25, thus tending to force the door panel C into closed position. Latching blocks 34 are prevented from moving circumferentially toward the door opening in a manner which would tend to release the panel from the opening. In fact the only way that the latching blocks can be released is by holding the center segment 31 against the bar 25 and pulling one of the end segments away from the body of the drum in a generally radial direction.

When the drum is rotated and the weight of the articles being treated Within the drum bears directly against the door panel C, the resulting force tending to open the door will act against the center segment 31 of the latching strap C and tend to increase the frictional force which resists the removal of the blocks 34 from their operating position shown in FIGURE 3. Thus the latching straps C are inherently self locking to prevent accidental release and opening of the door panel B during operation of the drum.

While the invention has been shown and described with reference to a specific embodiment thereof this is for the purpose of illustration rather than limitation and other modifications and variations will be apparent to those skilled in the art upon a reading of the specification. Accordingly the patent is not to be limited in any manner inconsistent with the extent to which the progress in the art has been advanced by the invention.

I claim:

1. Apparatus for plating, blackening, pickling and the like comprising (l) a generally cylindrical drum designed for rotation about a longitudinally extending axis, said drum being incomplete in the sense that it has in its body portion an elongated opening corresponding to a subtended dihedral angle of a magnitude between about 60 and about (2) jambs flanking the long sides of said elongated opening; (3) an elongated closure of arcuate configuration completing the drum, the outer longitudinal edges of said closure mating with the inner faces of the jambs; (4) rib structure extending longitudinally of the exterior face of said closure; and (5) one or more transversely directed spring metal latching members of doublegambrelled shape the central portions of which engage said rib structure and the end portions of which engage the outer faces of said jambs.

References Cited UNITED STATES PATENTS 2,886,505 5/1959 Singleton et al. 204-213 3,337,442 8/1967 Kiefer et al 204-213 3,340,170 9/1967 Marulli et al 204-213 3,394,071 7/1968 Gill 204-213 JOHN H. MACK, Primary Examiner W. B. VAN SISE, Assistant Examiner U.S. Cl. XR. 

